Use of brackets in class files

I’m working on creating a component of my own and in checking out the .as files for the current component set I see the following definitions after package{ and before class{

[Event(name=“progress”, type=“”)]

Is the use of this syntax documented somewhere? I’ve seen the same thing used when embedding a font from a users system but I can’t find where Adobe describes how to use it. Specifically I’m wanting to use this for styling my component just like the Flash components are styled.